Disposable diapers are well known articles of manufacture that are worn by infants and incontinent persons. Disposable diapers are worn about the lower torso and are intended to absorb and contain urine and feces, thereby preventing such body exudates from soiling, wetting, or otherwise contaminating articles (e.g., clothing, bedding, etc.) that come in contact with the diaper wearer.
In general, disposable diapers have the same basic structure comprising an absorbent core encased between a liquid pervious, user-contacting topsheet and a liquid impervious backsheet. The prior art, of course, teaches numerous variations of and elements in addition to the basic topsheet, backsheet, and absorbent core arrangement. For example, an improvement in performance of disposable diapers has been achieved by the addition of elastic means along portions of the diaper contacting the wearer's thighs or waist, thereby providing elasticized leg or waist openings when the diaper is worn.
When using a disposable diaper having elasticized leg openings, the diaper user fits the diaper on the wearer and fastens it about the wearer's waist by a fastening device to thereby affect a side closure. Fitting the diaper about the wearer usually requires the front and back waist portions of the diaper to overlap each other. Disposable diapers are provided with a fastening device having a first member and a second member which engage each other to provide such a side closure in the front and back waist portions. Since proper and sustained fit about the waist and legs of the wearer is vital for optimal performance in terms of minimizing leakage of exudates out of the diaper, a fastening device must be able to provide an effective side closure in which the front and back waist portions are maintained in an overlapping configuration. Thus, the first and second members must be designed to securely engage each other so that they do not separate due to peel forces and shear stress that are encountered by the fastening device during use.
Another important design criteria in providing a fastening device on a disposable diaper is that the fastening device be comfortable for the wearer. In use, the fastening device may come in contact with the bare skin of the wearer. For example, if one of the members of the fastening device is disposed on the outside of the diaper it may not be completely covered during use such that it will come in contact with the wearer, or since the waist portions are generally highly flexible areas which can fold under during wear, a portion of the fastening device can be exposed to the skin of the wearer. Thus, if the fastening device is "skin friendly" (i.e., it does not contain sharp, rough or jagged edges, elements or prongs) the fastening device should not abrade or irritate the skin of the wearer.
A number of concepts have been proposed for adhesively fastening a disposable diaper about the waist of the wearer. For example, U.S. Pat. No. 3,848,594 issued to K. B. Buell on Nov. 19, 1974, teaches an adhesive tape fastening system for effecting a side closure having an improved manufacturer's joint, referred to as Y-bond. Adhesive tape fasteners have, however, a number of shortcomings, one of which is that they are easily contaminated by oils and powders that come in contact with the adhesive on the fastening tapes such that the adhesive does not adhere to the diaper with suffient strength to provide an effective side closure. In addition, an adhesive tape fastener may rip the backsheet of the diaper during the process of unfastening it to check if the diaper has been soiled or to adjust its fit, thereby leaving a hole in the backsheet of the diaper and rendering the fastener unrefastenable and the diaper unuseable. Thus, it would advantageous to provide a fastening device that is not easily contaminated by oils and powders, that is more convenient to refasten, and that does not render the diaper or the fastening device unuseable after unfastening.
Since adhesive tape fasteners are not practical for use on reuseable diapers, a number of concepts have been proposed for providing a reuseable diaper with a mechanical fastener having hooks and loops disposed on the body of the diaper. For example, U.S. Pat. No. 3,359,980 which issued to C. L. Rosenblatt on Dec. 26, 1967; U.S. Pat. No. 4,402,690 which issued to R. Redfern on Sept. 6, 1983; and U.S. Pat. No. 3,618,608 which issued to M. E. Brink on Nov. 9, 1971 all teach reuseable diapers having hook and loop type fasteners.
While hook and loop type fasteners generally provide a fastening device that is not easily contaminated by oils and powders and is more convenient for refastening than adhesive fastening tapes, hook and loop type fasteners are generally not comfortable nor skin friendly. The "hook" members may have sharp, jagged edges or jagged members that can puncture, abrade or irritate the skin of the wearer. This is especially true of hook and loop type fasteners wherein the hook elements are formed by cutting a filament loop. Jagged edges are formed on both the hook and on the resulting non-functional prong that is formed in the cutting process. Thus, it would be advantageous to provide a mechanical fastener that is capable of resisting the peel forces and shear stress that are encountered during use and that is comfortable for the wearer because it is skin friendly so that it minimizes discomfort and skin irritation of the wearer.
It is, therefore, an object of the present invention to provide a disposable diaper having an improved fastening device.
It is a further object of the present invention to provide a disposable diaper having a fastening device that maintains the fit of the diaper at the waist and at the elasticized leg openings during wearing.
It is an additional object of the present invention to provide a disposable diaper having a fastening device that is not easily contaminated by oil and powders and that is refastenable.
It is another object of the present invention to provide a disposable diaper having a fastening device that provides wearer comfort and ease of handling for the user.
It is a still further object of the present invention to provide a disposable diaper having a mechanical fastening device that is skin friendly and able to resist the peel forces and shear stress encountered during use.
These and other objects of the present invention will be more readily apparent when considered in reference to the following description and when taken into connection with the accompanying drawings.